Needle boards are components of needle machines for manufacture of nonwoven fabric or needle felt and are fitted with special needles. The needle machines are used for strengthening/thickening of fibrous materials, fibers and continuous filaments. Products such as spunbond, artificial leather, artificial suede, and needle felt which can contain nonwoven fabric are manufactured. The needles have an L shape due to their fastening hooks, the so-called crutch or crank, and are passed through drilled holes in the needle board and fixed. The needles are subject to major stress and damaged over time.
Besides needles with crutches or cranks, there are also needles with fastening areas, which are formed by the thickening of an end, as is well known, e.g., from JP 11350328 A or DE 10 2011 016 755 B3. The present invention may refer both to the separation of needles, which are used for fitting a needle board, and to needles, such as sewing needles or embroidering needles or knitting needles, nails or nail-like pins in other areas of application.
So that now the needle board can be fitted with the needles, these needles must be removed from a removal site. The removal site is known from the state of the art in very different embodiments.
For example, an oscillating conveyor, which is arranged in a carriage unit of a needle-loading and needle-unloading device and has a receiving element for a supply of primarily unorganized needles appears from DE 3941159 C1. The oscillating conveyor has an outlet, in which the needles are separated and oriented with their crutches or cranks in the same direction. The separated needles oriented in the same direction are then placed at right angles on a belt-like linear conveyor, which advances each time by one step by means of a stepper drive when a new needle shall be driven into the needle board. A gripper grasps the last corresponding needle of the needles fed with the belt conveyor and then pivots to the needle board to carry out the fitting. The separation of the needles to be provided requires two conveying units—an oscillating conveyor and a belt conveyor—and thus is relatively costly. In addition, the prior-art separating device needs a lot of space within the overall device.
Another device for separating and feeding needles, with which a needle board shall be fitted, is well known from EP 1953287 A1. The needle feed comprises a receiving element for the needles in the form of a filling funnel with a vibration device and with a filling device in the form of two parallel threaded spindles, rotating in the same direction, in the motions of which the needles are separated at a desired distance and are placed in groups, such that they can be grasped and picked up by a gripping jaw/multiple gripping jaw. Stepping motors are used for rotating the spindles. The separating device in question requires a high design effort and takes up a lot of space.
DE 10 2011 016 755 B3 shows a device, which, besides other functions, is also used to fit a needle board with needles, and a robot with a tool arm picks up fresh needles from a removal site. Since the robot is equipped with an articulated tool arm and tool, it can remove needles even from a removal site, which is the reason why the labor cost is extremely low. The robot has a high freedom of movement, which allows the free needle pickup selectively, in relation to a selected needle in the removal site. Due to the articulated tool arm at the robot, the design effort of a conventional needle feed is avoided. The removal site is, e.g., arranged on a base plate of the robot. During this needle removal, the removal is preceded by a detection operation by means of a camera or a laser scanner or additional detection devices. The data are electronically collected and processed in a separate computer, such that the position of the needle to be picked up is determined and then the orientation of the tool arm with the gripper takes place. This solution of a robot operating by means of image detection is “binpicking.” This type of needle removal is very costly, since the robot has to detect a high-resolution image of the needle. A high-resolution image detection is very costly and requires a costly software. Many programming hours and tests are necessary to calculate the undefined gripping position and the gripping location of the needle to be grasped at the removal site. The gripping position describes where the crutch or crank/hook must be arranged. The gripping location depends on the position of the needle in the removal site. The needle detection and needle grasping take place relatively slowly in the state of the art in question. Approx. 5 seconds pass by from the detection of the image until the picking up of the needle. The computerized selection of a needle, the going there and grasping have, moreover, a hit ratio of approx. 85%, which is in need of improvement. The seconds needed to grasp the needle play a very large role in the goal of fitting a needle board with, for example, approx. 50,000 needles.